This invention is directed to coating compositions containing a particulate fluorocarbon resin as a texturing agent. More particularly, this invention is directed to fluorocarbon resin-based coating compositions containing large particle size particulate fluorocarbon resin as a texturing agent.
Fluorocarbon resins are known for their outstanding durability, that is, their provision of a tough finish which is not readily disposed to crazing or chalking with fluctuations in weather conditions. Fluorocarbon resins are especially applicable in the building panel industry for use in preparing durable surfaces for exterior use.
Textured surface are not new in the art and several methods are available for producing them. U.S. Pat. No. 3,389,013 outlines several methods. A first method employs "wrinkle materials". These contain drying oils, which, upon curing, drying, or aging, form irregular films resembling wrinkles. A second method involves the use of what is called a spatter coat. This is generally sprayed over the surface to be coated in the form of discrete particles which then coalesce and cover only part of the surface. A third method involves first forming a smooth finish with a film-forming material and then applying thereover a so-called texturing agent such as an organic solvent to change the smooth finish to a textured finish. A fourth method for obtaining textured finishes involves first applying a base coat, allowing this base coat to dry, and then applying a dissimilar top coat which contains a dispersion resin. The textured finish resulting from this method is thought to be caused by the contraction of the top coat, leaving part of the base exposed. Another method, the method claimed in U.S. Pat. No. 3,389,013, involves applying a composition comprising resinous film-forming material in particulate and in dissolved form, the resin in particulate form being present in sufficient amount and appropriate particle size to produce texturing. The textured coatings produced in this manner, however, are not homogeneous, that is, the final coating retains the original discrete particles without the intervening formation of a fused coating with the texturing agent. Although effective for use with many types of coatings, the aforedescribed texturing methods have a severely limited ability to successfully texture fluorocarbon resins. While fluorocarbon resins have many unique chemical characteristics, conventional texturing materials used therewith, such as polypropylene, typically change color, chalk or release from the coating composition upon exposure to external climatic conditions or exhibit marked yellowing upon baking for a short period. Because fluorocarbon resins exhibit such outstanding durability and provide excellent properties for exterior use, a method is needed to successfully texture these resins without detracting from the excellent properties of the fluorocarbon resin.